The present invention relates to a cigarette holder which is provided with a tar removing cartridge for filtering the smoke passing through said cigarette holder, and, more particularly relates to an improved structure for such a tar removing cartridge, which gives it a superior performance in filtering tobacco smoke.
In the past, a number of different structures have been proposed for a cigarette holder equipped with a tar removing cartridge. Many of these have had a renewable tar removing cartridge. Such a renewable cartridge can be removed from the cigarette holder when the cartridge's efficiency in filtering smoke has dropped below an acceptable level, and can then be replaced by a fresh cartridge.
The filtering effect of such a tar removing cartridge needs to be durable, because the user will be reluctant frequently to change the cartridge. Thus, the number of cigarettes whose smoke can be passed through the tar removing cartridge, before the efficiency of the tar removal action provided by said cartridge is deteriorated to an unacceptable level, is a critical factor with regard to the design of such a cartridge. Further, low cost of mass production of the cartridge is also a critical factor, because the salability of such goods is rather price sensitive.
Further, in view of the desirability of providing a good filtering effect for the tobacco smoke passed through such a tar removing cartridge, which is very important in view of the severely high rates of lung cancer, bronchitis, heart disease, and other ailments directly attributable to smoking of tobacco, it is important that the percentage of the tarry substances present in tobacco smoke which are removed therefrom by such a tar removing cartridge should be high at all times during its usable life span. In other words, the tar catching ratio, or the efficiency of catching tarry particles, should be high initially, and should remain quite high, until the cartridge is ready to be discarded for a fresh one.
Conventional tar collecting cartridges based upon the principle of ejecting the tobacco smoke against a barrier wall so that tarry particles are caught by the barrier wall while the smoke gases only are diverted away from the barrier wall have the general advantage that they have a relatively large tar collecting capacity, while on the other hand they have the general disadvantage that they are rather deficient in removing finer and smaller tarry particles.
A simple filter device such as is conventionally used for a filter tip for a cigarette is not properly suitable for use by itself for a tar removing system for such a tar removing cartridge, because, although such a filter device is effective at removing a large proportion of the tarry particles from smoke including the finer or smaller particles, it tends very quickly to become choked or clogged up with the coarser or larger tarry particles, and thus to lose its filtering ability. This effect means that the usability of such a filter device is really best restricted to applications wherein it is only required to filter the smoke so as to remove the finer or smaller particles which are not great in amount.